Nucleic acid oxidation is important in the etiology and treatment of disease. For instance, ionizing radiation causes cancer and destroys tumor cells by damaging DNA. DNA damage is also involved in aging and a variety of other diseases (e.g. Xeroderma Pigmentosum, cystic fibrosis, myocardial infarction). The goals of this research are to understand how lesions produced in DNA as a result of oxidative stress are repaired, replicated, and react to form other lesions. We are also developing tools for selectively detecting DNA lesions. Much of our effort focuses on oxidized abasic lesions, which are incapable of forming Watson-Crick hydrogen bonds. Contrary to what was previously believed, oxidized abasic lesions interact with polymerases in distinct ways from each other and from an abasic site (AP) resulting from formal hydrolysis of a nucleotide's glycosidic bond. Hence, the inability to form Watson-Crick hydrogen bonds does not mean that a lesion is noninstructive. We will use synthetic chemistry to synthesize analogues, rapid-quench kinetics to determine polymerase mechanisms, as well as shuttle vector experiments to determine what structural properties of the individual lesions give rise to their observed effects in cells. We will also examine the repair of lesions that would appear to require unusual handling by DNA repair enzymes. Finally, we will develop and employ reagents that enable us to selectively detect oxidized abasic lesions. These tools will enable scientists to correlate unique biological effects of lesions with their formation by various oxidizing agents. Relevance to public health: Oxidative nucleic acid damage plays an important role in aging, as well as the etiology and treatment of genetic diseases, such as cancer. This fundamental research is valuable to understanding the etiology and treatment of diseases such as cancer. Furthermore, the reagents developed by us for selectively detecting oxidized abasic sites will be valuable biotechnology tools. [unreadable] [unreadable] [unreadable]